In the preparation of liquid treatment compositions, it is always an aim to improve technical capabilities thereof and aesthetics. The present invention specifically relates to the aim of improving on the traditional transparent or opaque aesthetics of liquid compositions enveloped within water-soluble films. It is also an aim of the present invention to convey the compositions technical capabilities through the aesthetics of the composition. The present invention relates to liquid compositions comprising optical modifiers that are capable of transmitting light such that the compositions appear pearlescent. Said liquid compositions are enveloped within water-soluble films to produce a unitised dose product.
Pearlescence can be achieved by incorporation and suspension of a pearlescent agent in the liquid composition. Pearlescent agents include inorganic natural substances, such as mica, bismuth oxychloride and titanium dioxide, and organic compounds such as, fish scales, metal salts of higher fatty acids, fatty glycol esters and fatty acid alkanolamides. The pearlescent agent can be acquired as a powder, suspension of the agent in a suitable suspending agent or where the agent is a crystal, it may be produced in situ.
However liquid laundry or hard surface cleaning compositions necessarily have relatively low viscosity, especially at high shear, such that they may be poured. Typically a laundry composition has viscosity of less than 1500 centipoises at 20 s−1 and 21° C. Such products generally also have low viscosity at low shear, resulting in any particulates having a tendency to separate from the liquid composition and either float or settle upon storage. In either scenario this gives an undesired, non-uniform product appearance wherein part of the product is pearly and part of it is clear and homogeneous.
Detergent compositions and pearlescent dispersions comprising pearlescent agent fatty acid glycol ester are disclosed in the following art; U.S. Pat. No. 4,717,501 (to Kao); U.S. Pat. No. 5,017,305 (to Henkel); U.S. Pat. No. 6,210,659 (to Henkel); U.S. Pat. No. 6,835,700 (to Cognis). Liquid detergent compositions containing pearlescent agent are disclosed in U.S. Pat. No. 6,956,017 (to Procter & Gamble). Liquid detergents for washing delicate garments containing pearlescent agent are disclosed in EP 520551 B1 (to Unilever). None of these prior art documents discuss the compositions in the unitary form of a liquid composition comprised within a water-soluble package.
The Applicants have found that the issue of suspension can be solved by incorporation of the composition comprising pearlescent agent into a unit dose where lack of stability and suspension are not as noticeable. The Applicants have however found that the addition of pearlescent agent, to a liquid composition intended for packaging into a unit dose, did not result in as significant a change in aesthetic as was expected. Upon further investigation, the Applicants have found that pearlescence in a unit dose has different difficulties owing to the low level of water in the compositions required when enveloping in a water-soluble film.